I trawled through many forum and got my built-in LAN Atheros AR8131 works perfectly 1st go with this kext. Read all about it here:
http://www.insanelymac.com/forum/ind...=181343&st=160
Download here:
http://www.insanelymac.com/forum/ind...=post&id=70249
This kext is 64-bit but works flawlessly with 32-bit as well!

I am trying to get the built-in GMA X3100 working as I have managed it succesfully (with an older Leopard kext AppleIntelGMAX3100FB 156KB ) on my laptop HP 6710b but so far, no luck. Anyone has success with the built-in graphic on this G31M-ES2L rev 2 board yet ? Should I give up and use something like the cheap nVidia 8400GS